Coloration of fruit



Patented Oct 11,1938 2,133,064

UNITED- STATES PATENT v rr-ice v I comas rfix r morr .David G.'Ulrey,'lampa,Fla.,asaignortoH.Grady ZellnerJmkelamLl'la.

No Application July as. me. Serial No. 93,311

3 cum.) (cl. -10:)

This invention relates to the coloration of continuous or it may constitute a discontinuous fruit, more particularly ,to an improved method phase by being emulsified in water with suitable of treatingcitrus fruits to enhance their varietal emulsifying agents. In either case, the fruit is color. immersed in and contacted by an excessive 5 It is well known in the art that the color 0! amount of a solvent for the oily and wan con- 5 fruits, especially citrus fruits, is one of themore stituents of the fruit. In these circumstances, important factors which govern the price of such therefore, excess leaching or removal of the products. In view of this it has been proposed natural preserving agents of the skin obtain. 7 in the past to'enhance the varietal color of citrus According to the present method a suitable 10 fruits,'such as oranges, by applying a dye therecertified water insoluble, oil soluble-dye is em- 10 to. One commercial method which has been ployed in dry powdered form and this is applied employed consists essentially in dissolving a to a fruit, such as an orange, which has been water insoluble, oil soluble dye in a relatively subjected to such a preliminary treatment that strong non-aqueoussolvent and applying this vethe fruit itself contains a thin extenuated iilm of hicle, consisting ofthe solubili zed dye,to the fruit. solvent or dispersing medium. In these circum- 15 when the fruit'is contacted with such a dye bath stances, therefore, the fine the particles are the solvent, having a solubilizing action upon the dusted on or applied to the him of solvent or disoily and'waxy constituents of the skin, tends to parsing medium and are dissolved or dispersed dissolve these and ultimately to deposit the dye uniformly through the iilm. Since the film is of in the peel of theftuit. V such character that it has a penetrating or dis- 20 A disadvantage of this older method is that solving action on the-skin, the dye is thus carthe' fruit is contacted with a relatively large ried into and transferred to the peel oi the fruit. quantity of the solvent vehicle for a protracted with this type of operation a minimal quantity period of time. Due to this the solvent tends to or the solvent or dispersing agent may be emsolubilize and extract or leach out" a considerployed, thus limiting to a considerable degree the 25 able quantity of the naturaljpreserving agents of amount of solubilizing and removal of the oily the fruit,'namely the waxes and/or oiis. v and waxy constituents of the fruit.

The object of the present invention is to pro- In operating the invention the fruit, such as vide a process of treating fruit to accentuate or oranges, may be subjected to a preliminary treatenhance its natural color without too great a ment. as for example by immersion in a clean- 30 removal of the .natural oleaginous preserving ing or detergent solution. This may be eifected agent. e o k in the well known manner by utilizing apparatus Another object isto-provide an improved 'm'ethnow available n e m- From the 788111118 0d of coloring citrus fruits. tank the oranges may be passed, either continu- A Iurther object is to provide a method for ously or intermittently, to'a rinsing tank to re- 35 coloring citrus fruits whereby a dye is dissolved move any adherentwashing solution. The thus in avehicle coating on the surface "of the fruit; I washed and rinsed fruit is then passed through A'still further object is to provide an improved a tank containing a solvent for the dye which is method of coloring citrus iruit'whereby a water to be employed. 8uch solvent may comprise any 40 insoluble, oil soluble dye is dissolved in situ on suitable organic solvent for the dye, such as light 40 the peel of the fruit. I hydrocarbon fractions. alcohols. ketones, vege- With these and other equally important and table oils and the like. related objects in view, the invention comprises The oranges or other fruit which are immersed the treatment, of fruits, particularly oranges, in the dye bath may rapidly be removed therewith a powdered water insoluble, oil soluble dye r m by suit le conveying mechanism and 45 under such circumstances that the dye is unipassed over a series of transverse rollers whereformly dissolved in a surface him of solvent or on they are rapidly rotated to establish a condispersing medium preliminarily applied to the tinuous thin film of the solvent over the surfruit. race of the fruit. When such thin film has been As has been indicated hereinbefore, the typical established the fruit may be passed into and 50 method of dyeing-citrus fruits comprises the imthrough a dye applicator. In this element dry mersion of the fruit in a dye bath. This dye powdered dye is deposited on the fruit and prefbath itself comprises a water insoluble, oil soluerably while the latter is substantially continuble dye dissolved in a solvent. According to proously rotated. The dye may be applied to the skin posals in the past the solvent dye phase may be of the fruit by means 0! a suitable sifting mechs5 After treatment in the dye applicator the treated fruit may be remotied and subjected to a builing action to mechanically yvork the liquid film, containing the dissolved or dispersed dye,

into the .skin. Thereafter the fruit may be rinsed with water to remove excess dye and may: be subfected to any suitable type of treatment. Thus the fruit which has been dyed in the manner described may be passed into ;,a tank contain-. ing a wax emulsion so as to deposit the desired quantity of wax on the peel, andsueh waxed fruit,

may thereafter be polished in the manner well lmown in the art. g

In another method of operation the fruit, such as oranges, may be washed with the detergent solution and then passed into a tank containing an aqueous soap solution maintained at relatively elevated temperatures of the order of from BOto 120 F. or more. The fruit may be maintained in the soap solution for a relativeiyshort period of time or for aprolonged period of time. If the treatment in the 'soap'solution is orshort duration, the solution acts upon the waxy constituents of the skin to remove such waxy constituents to some extent and to thus permit more rapid pene tration of the dye. After a short treatment in the soap solution the oranges are removed end passed over. a series of conveyor rollsto the dye applicator. The fruit entering the dye application, as will be appreciated, is covered with a thin film'of the soap solution. The dry powdered dye is ap.-

plied uniformly to the Truit and preferably while the latter is rapidly rotated so as to insure a uniform deposition of dye on the film. The thiis applied dye adheres to the film and is taken and dispersed therethrough. During the mechanical working 'action efi'ected by the rollers the dispersed dye is transferred to and deposited in the peel of the fruit. 7: is

After treatment in the dye applicator the oranges may be treated, as by rinsing'with water, to remove excess dye and maythenbe passed to a waxing tank and'clried and polished in the b0 manner well Known to those skilled in the art. l

. .Infanotherimethod of operation the organges, which may first be subjected to a preliminary cleaning, as bya detergent solution, are passed into a tank containing a solvent or soap solution maintained at relatively elevated temperatures. The oranges may belretained in this ,tank for a period of time sufllclently prolonged to insure substantially complete removal of the oily or waxy constituents. This period of contact, as wilkbe app eciated, will vary depending upon the par- ,ticular type of solvent or soap solutionemployed, the concentration of the solution and the tern:- perature. After treatmentin this dewaxing tank the oranges, now substantiallycompletely 'dedyed fruit. 7

nuded of the waxy layer and containing a thin extenuated film of solvent .or soap solution, are passed through the dye applicator in the manner herelnbefore described. In thisparticular oper-I ation, since the repellentwaxy constituents have largely been removed; the dye contained either in the solvent or soap vehicle rapidly penetrates and is depositedin the peel'of the fruit. After .suchdyeing operation the oranges may be rinsed, waxed, dried and polished, or subjected to any other desired type of subsequent treatment.

It will be understood that the essential treatment according to the present invention involves the use of a dry dye and theestablishment of a thin film of liquid on the surface of the fruit, which film of liqui f presents the capability of absorbing the dye and transferring it to the peel of the fruit; Thlstype of operation thereiore avoids the necessity of using a dye bath contain-,- ing large amounts of solvent and permits a more accurate control of the tinctorial efiect of the dye treatment. 7 f

It will be understood thatfwitlnn the scope of the invention various modified processes mayv be employed. 1 Thus, if desired, the fruit to be treated may'be dewaxediniione tank with one type of s0lvent, .may: then be rinsed and then immersed in or sprayed by yet another type of solvent which hasja preferentialsolubilizingaction upon thegdye to be employed. With this type of treatment, therefore, optimum conditions of washing, partial or complete fdewaxing ordyeing may be established. a V,

While preferred modifications of the invention have been described, it is to be understood that these are given as exemplifyingthe underlying principles involved and not as limiting the invention; to these particular methods. Y

Iclaim: v i l A process of enhancing the varietal color of whole citrus fruitwhich comprisesewashing the fruit,applying to the skin of the washed fruit a thin continuous film of an aqueoussoap solution, applying to the fruit a quantity'of dry powdered 'o'il soluble, water insoluble dye which is dispersableby said soap solution.,

2. A process of enhancing the varietal color of whole citrus fruit which comprisesapplying to the skin of:the', fruit a thin film of an aqueous soap solution, uniformly'depositin'g on such liquid film adry ipowdered water insoluble, oil soluble dye, washing the fruit to remove excess dye and then waxing and polishing the fruit.

, ,3. A process of enhancing thevarietal colorof whole citrus fruit Ewhich comprises washing the fruit, applying to the skin oflthe washed fruit a thin continuous film of an aqueous soap solution,

applying to the fruit a quantity of dry powdered oil soluble, water insoluble dye which is dispersable bysaid soap solution, washing the fruit to remove excess dye, and subsequently waxingrthe DAVID G. 

